Prof Simon Fishel, the care body’s managing director, said he believed it could be a major cause of recurrent miscarriage.

With proper treatment, he added, the number of couples having healthy babies increased to 38 per cent, a similar proportion to other infertility patients of the same age.

The findings were published in the journal Reproductive Biomedicine Online.

The genetic fault means the embryo is unlikely to implant in the womb or do so sufficiently, causing late miscarriage or growth problems in the baby.

If the woman is the carrier of the gene, she is also at risk of complications such as blood clots.

Prof Fishel, who led the findings, said: “Very recently a new genetic marker has been found that predisposes couples to the risk of miscarriage, which we call the C4/M2 variant.

“In addition to the risk of implantation failure and miscarriage, it is linked to blood- clotting disorders, pre-eclampsia and low birth-weight babies.

“What I do find remarkable is that in the population of patients studied, the man has the same chance as the woman to pass on this variant to the developing embryo and disturb successful implantation. Where the genetic variant exists, the chance of delivering a baby is reduced to one in four of that of fertile couples.”

Care Fertility intends to screen patients for the faulty gene so they can be treated appropriately.

A spokesman for the Miscarriage Association said: “We always welcome new research into factors that can increase the risk of miscarriage, so we’ll be looking closely at these findings with the help of our research expert advisers.”